1. The Field of the Invention
The present invention relates generally to a method and apparatus for driving a display device. More specifically, the present invention relates to methods and systems for improving a response speed of a liquid crystal display.
2. The Relevant Technology
Liquid crystal displays (LCD's) are widely used in a number of products, such as flat panel televisions, computer screens, mobile telephone displays, and the like. One drawback common to liquid crystals is their inability to quickly and consistently respond to rapidly changing images. The response time of liquid crystals can be slow, and may vary depending on the starting and target graylevels produced by the liquid crystals. This slow response can result in poor video quality.
To compensate for slow liquid crystal cell response, one technique applies an amplification factor, or “overdrive” voltage, to pixel changes during a frame transition. This adjusts the time required to reach the target frame, thereby improving the motion picture quality of LCD panels and reducing motion blurriness.
With this technique, a lookup table is created containing overdrive levels corresponding to various different starting graylevels and target graylevels. An overdrive parameter is retrieved from the lookup table that corresponds to the starting graylevel of the preceding frame and the target graylevel of the current frame. This retrieved overdrive parameter is then applied to the liquid crystal with the intent of causing the liquid crystal to produce the appropriate response time.
Selecting an appropriate overdrive parameter can be difficult because the response time of a liquid crystal varies depending on the ambient temperature. Therefore, the overdrive parameters stored in a single lookup table are only valid at a single ambient temperature. Temperature variations are particularly problematic for mobile display panels, which are often exposed to relatively wide temperature variations.
One solution to this problem is to store overdrive data calibrated at different temperature settings in multiple lookup tables. Each lookup table is calibrated for a different temperature setting in order to achieve accurate and reliable liquid crystal response times in different temperature environments. However, this solution inevitably increases the memory bandwidth required by the overdrive process, thereby driving up the memory cost of the overdrive unit. This approach may not be feasible for certain applications that operate on systems with limited resources.
The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.